The present invention relates generally to medical devices and in particular aspects to medical products and methods for treating fistulae including those having a primary opening in the alimentary canal.
As further background, a variety of fistulae can occur in humans. These fistulae can occur for a variety of reasons, such as but not limited to, as a congenital defect, as a result of inflammatory bowel disease, such as Chron's disease, irradiation, trauma, such as childbirth, or as a side effect from a surgical procedure. Further, several different types of fistulae can occur, for example, urethro-vaginal fistulae, vesico-vaginal fistulae, tracheo-esophageal fistulae, gastro-cutaneous fistulae, and any number of anorectal fistulae, such as recto-vaginal fistula, recto-vesical fistulae, recto-urethral fistulae, or recto-prostatic fistulae.
Anorectal fistulae can result from infection in the anal glands, which are located around the circumference of the distal anal canal that forms the anatomic landmark known as the dentate line. Approximately 20-40 such glands are found in humans. Infection in an anal gland can result in an abscess. This abscess then can track through soft tissues (e.g., through or around the sphincter muscles) into the perianal skin, where it drains either spontaneously or surgically. The resulting void through soft tissue is known as a fistula. The internal or inner opening of the fistula, usually located at or near the dentate line, is known as the primary opening. Any external or outer openings, which are usually located in the perianal skin, are known as secondary openings.
The path which these fistulae take, and their complexity, can vary. A fistula may take a take a “straight line” path from the primary to the secondary opening, known as a simple fistula. Alternatively, the fistula may consist of multiple tracts ramifying from the primary opening and have multiple secondary openings. This is known as a complex fistula.
The anatomic path which such fistulae take is classified according to their relationship to the anal sphincter muscles. The anal sphincter consists of two concentric bands of muscle, the inner or internal sphincter and the outer or external anal sphincter. Fistulae which pass between the two concentric anal sphincters are known as inter-sphincteric fistulae. Those which pass through both internal and external sphincters are known as trans-sphincteric fistulae, and those which pass above both sphincters are called supra-sphincteric fistula. Fistulae resulting from Crohn's disease usually “ignore” these anatomic planes, and are known a “extra-anatomic” fistulae.
Many complex fistulae consist of multiple tracts, some blind-ending and others leading to multiple secondary openings. One of the most common complex fistulae is known as a horseshoe fistula. In this instance, the infection starts in the anal gland (primary opening) at or near the 12 o'clock location (with the patient in the prone position). From this primary opening, fistulae pass bilaterally around the anal canal, in a circumferential manner. Multiple secondary openings from a horseshoe fistula may occur anywhere around the periphery of the anal canal, resulting in a fistula tract with a characteristic horseshoe configuration.
One technique for treating a perianal fistulae is to make an incision adjacent the anus until the incision contacts the fistula and then excise the fistula from the anal tissue. This surgical procedure tends to sever the fibers of the anal sphincter, and may cause incontinence.
Other surgical treatment of fistulae involve passing a fistula probe through the tract of the fistula in a blind manner, using primarily only tactile sensation and experience to guide to probe. Having passed the probe through the fistula tract, the overlying tissue is surgically divided. This is known as a fistulotomy. Since a variable amount of sphincter muscle is divided during the procedure, fistulotomy also may result in impaired sphincter control, and even frank incontinence.
Still other methods involve injecting sclerosant or sealant (e.g., collagen or fibrin glue) into the tract of the fistula to block the fistula. Closure of a fistula using a sealant is typically performed as a two-stage procedure, including a first-stage seton placement and injection of the fibrin glue several weeks later. This allows residual infection to resolve and to allow the fistula tract to “mature” prior to injecting a sealant. If sealant or sclerosant were injected as a one-stage procedure, into an “unprepared” or infected fistula, this may cause a flare-up of the infection and even further abscess formation.
A gastrointestinal fistula is an abnormal passage that leaks contents of the stomach or the intestine (small or large bowel) to other organs, usually other parts of the intestine or the skin. For example, gastrojejunocolic fistulae include both enterocutaneous fistulae (those occurring between the skin surface and the intestine, namely the duodenum, the jejunum, and the ileum) and gastric fistulae (those occurring between the stomach and skin surface). Another type of fistula occurring in the gastrointestinal tract is an enteroenteral fistula, which refers to a fistula occurring between two parts of the intestine. Gastrointestinal fistulae can result in malnutrition and dehydration depending on their location in the gastrointestinal tract. They can also be a source of skin problems and infection. The majority of these types of fistulae are the result of surgery (e.g., bowel surgery), although sometimes they can develop spontaneously or from trauma, especially penetrating traumas such as stab wounds or gunshot wounds. Inflammatory processes, such as infection or inflammatory bowel disease (Crohn's disease), may also cause gastrointestinal fistulae. In fact, Crohn's disease is the most common primary bowel disease leading to enterocutaneous fistulae, and surgical treatment may be difficult because additional enterocutaneous fistulae develop in many of these patients postoperatively.
Treatment options for gastrointestinal fistulae vary. Depending on the clinical situation, patients may require IV nutrition and a period of time without food to allow the fistula time to close on its own. Indeed, nonsurgical therapy may allow spontaneous closure of the fistula, although this can be expected less than 30% of the time according to one estimate. A variable amount of time to allow spontaneous closure of fistulae has been recommended, ranging from 30 days to 6 to 8 weeks. During this preoperative preparation, external control of the fistula drainage prevents skin disruption and provides guidelines for fluid and electrolyte replacement. In some cases, surgery is necessary to remove the segment of intestine involved in a non-healing fistula.
There remain needs for improved and/or alternative medical products, methods, and systems that are useful for treating fistulae. The present invention is addressed to those needs.